1. Field of the Invention
This invention relates to protective helmets which are useful for military, law enforcement and other applications. In particular, this invention relates to such helmets which provide protection against rifle bullets.
2. Description of the Related Art
Protective helmets are well known. Such helmets have been used for military and non-military applications. Examples of the latter include law enforcement uses, sporting uses and other types of safety helmets. Protective helmets used for military and law enforcement uses, in particular, need to be ballistic resistant.
Typical helmets are constructed to protect against bullet fragments. Protection against rifle bullets requires improvement over such helmets in view of the significantly increased energy possessed by rifle bullets. Helmets which protect against rifle bullets should be relatively lightweight and comfortable to wear. However, previously suggested helmets were relatively heavy.
Examples of rifle bullets against which protection is desired include the NATO M80 ball, the AK 47, the AK 74, the Russian LPS and the European SS 109, and the like.
The currently most popular military helmets are formed from aramid fibers, typically in the form of several layers of aramid fibers together with a resin material, such as a phenolic resin. Helmets formed of aramid fibers are disclosed, for example, in U.S. Pat. Nos. 4,199,388, 4,778,638 and 4,908,877. Although such helmets in general perform satisfactorily, they are fairly heavy. Also, such helmets do not provide enhanced protection against rifle bullets. One problem with helmets that are relatively heavy is that they are uncomfortable to the wearer. This may result in non-use or limited use of such helmets.
Examples of helmets which are designed to protect against projectile fragments (rather than rifle bullets) are set forth in copending U.S. patent application Ser. No. 11/706,719, filed Feb. 15, 2007, the disclosure of which is incorporated herein by reference to the extent not incompatible herewith.
It would be desirable to provide a helmet which has a reduced weight and also is resistant to penetration by rifle bullets.